Numerous types of catheters are actuatable by use of one or more pull wires incorporated therein. Among these types of catheters are steerable radio frequency ablation catheters having tips that are deflected in transverse directions by applying tension to one or more pull wires attached proximate the distal tips. Another type of pull-wire actuated catheter has a basket that can be radially expanded for such procedures as endocardial mapping and/or ablation, rotational atherectomy, thrombectomy, or embolectomy. Yet another type of pull-wire actuated catheter is a multi-electrode renal denervation catheter capable of deforming into a helical shape or other complex bend to achieve apposition against the inner wall of a renal blood vessel. While the pull wire actuation mechanism of the current technology may be employed with any of various types of catheters, the description herein will discuss, without being limited thereto, a PTCA guiding catheter having a deflectable tip.
A stenosis, lesion, or narrowing of a blood vessel such as an artery may comprise a hard, calcified substance and/or a softer thrombus material. There have been numerous interventional catheterization procedures developed for the treatment of stenoses in arteries. One of the better-known procedures is percutaneous transluminal coronary angioplasty (PTCA). According to this procedure, a narrowing in a coronary artery can be expanded by positioning and inflating a dilatation balloon across the stenosis to enlarge the lumen and re-establish acceptable blood flow through the artery. Additional therapeutic procedures may include stent deployment, atherectomy, and thrombectomy, which are well known and have proven effective in the treatment of such stenotic lesions.
In cases where the lesion targeted for treatment is located distant from a convenient vascular access location, the therapeutic procedure typically starts with the introduction of a guide catheter into the cardiovascular system from an easily reachable site, such as through the femoral artery in the groin area or other locations in the arm or neck. The guide catheter is advanced through the arterial system until its distal end is located near the stenosis that is targeted for treatment. During PTCA, for example, the distal end of the guide catheter is typically inserted only into the ostium, or origin of a coronary artery. A guidewire is advanced through a main lumen in the guide catheter and positioned across the stenosis. An interventional medical device or treatment catheter, such as a balloon dilatation catheter, is then slid over the guidewire until the dilatation balloon is properly positioned across the stenosis. The balloon is inflated to dilate the artery. To help prevent the artery from re-closing, a physician can implant a stent inside the dilated portion of the artery. The stent is usually delivered to the artery in a compressed shape on a stent delivery catheter and is expanded by a balloon to a larger diameter for implantation against the arterial wall.
Guide catheters typically have a pre-shaped distal curve that is sized and shaped for positioning in a main vessel to orient or direct a distal tip of the catheter into the ostium of a branch vessel. PTCA guide catheters, for example, may have a pre-shaped curve that fits within the aortic root and/or the ascending aorta for positioning the distal end of the catheter near or within the ostium of a left or right native coronary artery or a bypass graft, depending on the curve selected. Many guide catheter pre-shaped distal curves are also sized and shaped to span the width of the main vessel to support branch vessel intubation from a main vessel wall location that is contralateral, or generally opposite to the ostium of the branch vessel.
In some situations, the pre-shaped distal curve of the guide catheter may not be the correct curvature needed for the placement of the distal tip at a target site within the patient's cardiovascular system. When the pre-shaped distal curve is not a perfect match for the patient's anatomy often times the clinician will choose to withdraw the guide catheter from the patient's body and replace it with a guide catheter having a different distal curvature. Such a re-catheterization process not only increases the time required for the interventional procedure but also adds further arterial trauma. In some circumstances to avoid the steps of removing the less than optimally curved guide catheter and tracking a subsequent guide catheter with a more suitable pre-shaped distal curvature to the target site, the clinician may choose to use the indwelling less suitable guide catheter even though coaxial seating of the guide catheter distal tip within an ostium of a vessel may be very difficult or never achieved.
In order to address the ostium or aortic root geometry that may be encountered during an interventional procedure, medical device manufactures make and sell a vast number of guide catheters having a variety of pre-shaped distal curvatures, which consequently results in hospitals and clinics routinely maintaining inventories of a variety of guide catheters having various pre-shaped distal curvatures. In order to reduce the need to manufacture and inventory a vast number of guide catheters having various pre-shaped distal curvatures while still meeting the curvature needed for a particular interventional procedure, there remains a need in the art for a guide catheter that may be tracked to a target site within the patient's vasculature that once positioned has a distal portion or segment with a curvature that can be selectively changed to match the geometry of the target site.